Watering Plants When Their Temperature Says,
"I'm Thirsty!" By Don Comis
This summer, soybeans growing in a 13-acre circle in Texas are
getting water only when they ask for it.
Steven R. Evett, an Agricultural Research Service soil
scientist, and R. Troy Peters, a post-doctoral researcher in irrigation
engineering--based at the ARS Conservation and Production Research
Laboratory in Bushland, Texas--are evaluating a way to irrigate crops
automatically by taking their temperature. The system is based on
"Time-Temperature Thresholds" determined by ARS
Cropping Systems Research Laboratory
scientists in nearby Lubbock.
ARS plant physiologists John J. Burke and James R. Mahan of the
Lubbock lab first theorized that each crop has its own optimal temperature for
yield. With the experimental system, if plant temperatures stay above optimum
for a certain length of time, a cooling irrigation is automatically triggered.
Evett has had great success with temperature-guided drip
irrigation for corn and soybeans, achieving higher yields for soybeans and
greater water use efficiency for corn, than when these crops were watered based
on soil moisture.
Evett and Peters are now testing the system with center pivot
irrigation. The irrigation pipe rotates like the hour hand of a clock, tracing
a large circle every 24 to 72 hours as it sprinkles water.
This "hour-hand" pipe can be as long as one-half mile. Evett and
Peters are using one that's approximately 400 feet long. It has infrared
thermometers placed at regular intervals to read crop temperatures. Stationary
infrared thermometers in the field double-check readings. Temperature readings
are transferred wirelessly to a computer, which then sends instructions to the
The scientists are trying to determine how this fully automated
system affects crop yield compared with more traditional irrigation
Next year, they will evaluate automated center pivot irrigation
of cotton. Eventually they will go beyond merely turning water on and off
automatically, moving to a system that can precisely vary water applications in
a field where there are different soil types, or two or three different crops
ARS is the U.S. Department of
Agriculture's chief scientific research agency.